Telephone system



Dec. 18,1923. 3 1,477,874

w. H. HARRISON TELEPHONE SYSTEM Filed Dec. 50, 1919 4 Sheets-Sheet 1 L MAHGINAL F/y.

TELEPHONE SYSTEM Filed Dec. 50, 1919 4 Sheets-Sheet 4.

Patented Dec. 18, 1923.

earner WILLIAM! H. HARRISON, OF HULLIS, NEIT YORK, ASSIGNCIR T0 WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEVT YORK, I l. 1., A CORPORATION OF NEW YORK.

TELEPHONE SYSTEM.

Application filed December 30, 1919.

T 0 all whom it may concern:

Be it known that I, VVILLIAM H. :HAPBI- son, a citizen of the United States, residing at Hollis, Long island, in the county of Queens and State of New York, have invented certain new and useful Improvements'in Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to improvements in telephone systems and has particular reference to toll signaling circuits employed with transmission lines.

Heretofore it has been customary to employ physical and phantom lines for establishing connections between distant offices. It has been proposed to utilize these lines for the transmission of selective signals to operators at distant oflices to indicate thereat the particular lines over which it is desired to establish connections and to also transmit disconnect signals when calls are terminated. The various signals are further used to control the operation of repeater apparatus at intermediate offices.

An object of the invention is to transmit impulses over a signaling path common to a plurality of transmission lines by the operation of a plurality of relays which are responsive to a connection made to one of said lines.

Another object is to identify transmission lines taken for use by the transmission of signaling impulses of different current strength when connections are made to said lines.

Another object is to indicate at a distant or terminating oflice the particular line over which a connection is to be established, to signal an operator at a distant oflice when the connection is to be terminated, and to control the operation of repeater apparatus at an intermediate oflice. In accordance with this object signaling impulses are transmit ted from one distant ofiice through an intermediate office to another distant office over a signaling path including the sides of physi-.

cal lines in parallel. The disablement of the repeater apparatus is controlled by a switching device which is common to the transmission lines.

In the drawings, wherein the above and other objects are realized, Figs. 1 to a inclusive, taken together and arranged side- Serial No. 348,430.

by-side in the manner indicated by the circuit lines extending to the margins of the drawings, illustrate a preferred embodiment ol the invention; Fig. 5 is a diagram matic view of one of the cord circuits employed in connection with the invention.

Broadly, the invention is shown as consisting of two distant offices W and Z and two intermediate offices X and Y. Interconnecting these oliices are physical transmission lines A and C and the phantom line B. Means including a relay 27 is associated with the physical line A and momentarily energized for transmitting a selective signaling impulse from the office when a call is initiated upon said line, and a similar mechanism is associated with each of the other lines. A relay 2, common to all of the lines, is energized upon the initiation of a.

call on any one of them to establish thesignaling circuit which includes the two physical lines A and O in parallel.

At oilice X, the physical lines have associated therewith, the repeater apparatus Bil and RC these apparatus being indicated by dotted lines as they form no part of the present invention. Means preferably including polar relays 6 and T are placed in the signaling circuit and are operated, according to the potential of the signaling impulse transmitted, to effect the connection of the battery supply to the filaments of said repeaters.

The signaling impulse is transmitted. from office X over the sides of the physical circuits A and C in parallel to office Y, at which office, mechanism including polarized relays 81 and 82 is provided which is responsive to the signaling impulse to again control the transmission of a similar impulse from office Y to others Z. The physical lines at office Y are also provided, respectively, witn. repeaters HA and RC the filaments of which are rendered effective by the operation of relay 80 which is responsive to he energization of one of the relays 84', 86,

87, 94,-, 96 or 97, depending upon which of the polarized relays 81, 82, 91 or 92 is operated.

At office Z a mechanism is-provided pref erably including relays 203 and 20 i. either or both of which is responsive to the signaling impulses transmitted to said office' in order that the particular line over whlch a call is initiated may be indicated to the op- Operator at oflioe W initiates a call over Zine circuit"A.

The operator at oiiice W desiring to communicate with the operator at office Z over the line circuit A inserts the plug 13 of a link circuit D at ofiice W into jack 20, thereby causing the operation of relays 14 and 21 over a circuit established from battery through the winding of relay 14, the sleeve contacts of plug 13 and jack 20, and the winding of relay 21 to ground. The closure of the middle alternate contact of relay 21 causes the operation of relay 2 over a circuit extending from battery through the right-hand winding of relay 2 and the middle alternate contact of relay 21 to ground. Relay 1 operates in response to the closure of the middle armature and contact of relay 2. Relay 27 operates over a circuit extending from battery through the left-hand winding of relay 27, the right-hand alternate contact of relay 21, the middle normal contact of relay 4.7 and the middlenormal contact of relay 67 to the ground. The closure of the right-hand alternate contact of relay 27 causes the operation of relay 29 over an obvious circuit and the operation of relay 29 in turn causes the operation of relay 28 over an obvious circuit. Relay 28 in operating looks over a circuit extending from battery through the winding and right-hand contact of relay 28, the normal contact of relay 25 and the middle alternate contact of relay 21 to ground. The closure of the left-hand contact of relay 28 completes a circuit in which the windings of relay 27 are included differentially so that such relay releases and causes the release of relay 29. However relay 28 remains looked over the circuit previously traced therefor. During the interval in which relay 27 is operated a circuit is completed from the positive terminal of the 60 volt source of current through the left-hand alternate contact of relay 27, the upper winding bridged around the polar relays 3 and 4, the simplexedcoir ductors of line circuits A and C in parallel from office W tooflice X, the windings of relays 7 and 6 in series, the simplexed conductors of line circuits A and C in parallel from oflice X to oflice Y, the windings of polar relays 81 and 82 in series, the lower winding bridged therearound, the left-hand contacts of relays 98,97, 96 and 94 in series to ground. The direction of current flowing from negative to positive terminals of battery through. this circuit is such that relay 7 closes its left-hand contact. Relay 6, being marginal, is not responsive to a 60 volt current-of either polarity. A. circuit is then closed for relay 8 extending from battery, winding of said relay, and through the lefthand contact of relay 7 to ground. Relay 8 locks up through left-hand contact to ground at the normal contact of relay 5. The middle and right contacts of relay 8 are grounded and thereby complete the filament battery supply circuit for repeaters HA and- RG, associated with line circuits A and C respectively. The direction of current flowing through the winding of relay 81 is such, that said relay closes its upper contact, but the strength of current flowing through such circuit is insufficient to cause the operation of marginal relay 82. Relay 84 operates over a circuit extending from battery through the winding of relay 8 1 and the upper contact of relay 81 to ground. The closure of the left-hand alternate contact of relay 84: causes the operation of relay over an obvious circuit, such relay thereupon looking over a circuit extending from battery through the winding and left-hand contact of relay 80, the right-hand Contact of relay 98, and the left-hand contact of relay 88 to ground. The closure of the right-hand and middle contacts of relay 80 completes the filament battery supply circuit for repeaters HA and RC associated with the line circuits A and C respectively. Relay 84: remains operated during the continuation of the impulse being transmitted and during such operation a circuit is completed from the positive terminal of the 120 volt source of current through resistance 83, the right-hand alternate contact of relay 84, the right-hand normal contacts of relays 86, 87 and 88 in series, the upper winding bridged around polar relays 91 and 92, the simplexed conductors of line circuits A and C in parallel extending from'o'liice Y to oiiice Z, the windings of relays 203 and 204; in. series, the lower winding bridged therearound, the right-hand normal contacts of relays 227, 247 and 267 in series, the normal contact of relay 201, and the left-hand nor- The mal contact of relay 202 to ground. direction of current flowing through this circuit is such that polar relay 203 closes its upper contact to cause the operation of relay 226 over a circuit extending from battery through the Winding of relay 226, the right-hand normal contact of relay 221, the upper contact of relay 203, and the upper contact of relay 204 to ground. Lamp 223 is lighted over an obvious circuit and relay 226 is looked over a circuit completed from battery through the winding and middle contact of relay 226 and the left-hand nornav /eve m1 contact of relay 221 to ground. Upon the cessation of the impulse relay 203 returns toits normal condition. The closure of the left-hand alternate contact of relay 226 causes the operation of relay 228 over an obvious circuit and the closure of the right-hand contact of relay 228 completes a circuit in which the windings of relay 227 are included diiferentially thereby eifectively preventing the operation of relay 227.

Operator at ofii'ce Z answers the call extended orcr Zine circuit A.

The operator at oflice Z, observing the lighted condition of the lamp 223, inserts the plug 13 of alink circuit D thereat into jack 220, causing the operation of relays 14 and 221 over a circuit completed from battery through the winding of relay 14;, the sleeve contacts of plug 13 and jack 220 'and the winding of relay 221 to ground. The opening of the left-hand normal contact of relay 221 releases relay 226 to cause the extinguishment of the lamp 223. However, relay 228 does not release upon the opening of the left-hand alternate contact of relay 226, since 'a substitute circuit is completec therefor before such relay is fully released, which extends from battery through the winding and left-hand contact of relay 228, the normal contact of relay 225, and the make before break contact of relay 221 to ground. Thus the transmision of an impulse from oiiice Z to ofiice TV, upon the insertion of the plug 13 into the jack 220 in response to a c'all, is effectively prevented since the circuit for relay 227 is completed wherein the windings of said relay are included differentially, thus preventing the energization thereof. The operators at offices TV and Z may actuate their listening keys 15 in the respective link circuits D and thus establish means for communicating between the oliices over the line circuit A. The operators telephone circuits are not shown since they may be of any suitable type and are unessential to the proper understanding of the invention.

Operator at ofice W initiates a caZZ over the Zine circuit B.

The operator at oflice TV, desiring to con temporaneously extend another call to the office Z over the line circuit B. inserts the plug 13 of a link circuit D at oflice W, into the jack e0, causing the operation of relay 1% of the selected link circuit D and relay a1 of the line circuit B over a circuit similar to that previously traced for relays 14 and 21. The closure of the middle alternate contact of relay 4:1 produces no material effect upon the system inasmuch as relay 2 has: been previously operated due to the closure of the similar contact of relay 21. Relay 4-7 operates over a circuitfiextending from battery through the left-hand winding of relay 47, the right-hand altc" ate contact of relay t1, the righthand normal contact of relay 67, and the rigl'it-hand normal contact of relay 27 to ground. Relay 49 operates over a circuit from battery through the winding of said relay, right-hand alternate contact of relay 47 and right-hand normal contact of relay 27 to ground. The closureof the contact of relay t?) causes the operation of relay &8 over an obvious circuit, the latter relay locking over a circuit extending from battery through the winding and righthand contact of relay 4-8, the normal contact of relay 45, and the middle alternate contact of relay 41 to ground. The closure of the left-hand contact of relay 4-8 completes a circuit including the windings of relay 47 connected differentially, and the left-hand contact of relay &8, thus releasing relay d7. The release of relay 47 causes the release of relay 49, but the relay 48 remains operated due to the locking circuit previously traced therefor. During the operated period of relay 47, a circuit is completed from the negative terminal of the 60 volt source of current, through the left hand alternate contact of relay 47, the left-hand normal contact of relay 27, the upper winding bridged around polar relays 3 and 4, the simplexed conductors of line circuits A and C extending in parallel from office V? to oi'lice X, the windings of relays 7 and 6 in series, the simplexed conductors of line circuits A and C extending in parallel from office X to office Y, the findings of relays 81 and 82 in series, the lower winding bridged therearound, and the left-hand normal contacts of relays 98, 97, 96 and 94 to ground. The direction of current flow in this circuit is such as to cause rel'ay 7 to close its right-hand contact. Rel: j 8 remains energized in its previously described locking circuit and thereby continues to maintain the filament battery supply circuit for repeaters HA and RC associated with the line circuits A and C respectively at ofiice X. However, the strength of current flowingthrough the winding of marginal relay 6 is iusuiiicient to cause its operation. The current flowing through the windings of relays 81 and 82 is such as to cause relay 81 to close its lower contact, but is of insuflicient strength to cause the operation of marginal relay 82. Therefore, during the continuation of the-impulse, relay 86 is operated over an obvious circuit. The closure of the left-hand 'alternate contact thereof produces no material effect upon the system since relay is locked independently thereof. However, the closure of the right-hand alternate contact of relay 86 completes a temporary circuit extending from the negative terminal of the 120 volt source of current through resistance 85, the right-hand alternate contact of relay 86, the right-hand normal contacts of relays 87 and 88 in series, the upper winding bridged around relays 91 and 92, the simplexed circuits oi line circuits A and 13 extending in parallel from otfice Y to oflice Z, the windings of relays 203, 204 in series, the lower winding 7 bridged therearound, the right-hand normal contacts of rel'ays 227, 247 and 267 in series, the normal contact of relay 201, and left-hand normal contact of relay 202 to ground. The direction of current flow in this circuit is such that relay 203 closes its lower contact, but the strength of current is insulficient to cause the operation of marginal rel'ay 204. Therefore during the continuation of the impulse being transmitted, a circuit is completed for causing the operation of relay 246 which may be traced. from battery through the winding of relay 246, the right-hand normal contact of relay 241, the lower contact of relay 203, and the upper Contact of relay 204 to ground. Relay 246 in operating causes the illumination of lamp 243 and is looked over a circuit extending from battery through the winding and middle contact of: relay 246, and the left-hand normal contact of relay 241 to ground. Relay 246 also closes an operating circuit for relay 248 and the closure of the right-hand contact of relay 248 completes a circuit in which the windings of relay 247 are included differentially thereby preventing the operation of said relay.

Operator at ofiice Z answers the call being extended over time circuit B.

The operator at oliice Z observing the lighted condition of lamp 243, inserts plu f 13 of a link circuit D thereat into jac' 240 of the line circuit B causing the operation of relays 14 and 241 over a circuit similar to that traced for relays 221 and 14. The opening of the left-hand normal contact of relay 241 releases relay 246 to extinguish lamp 243 and although the opening of the left-hand contact of relay 246 opens the operating circuit of relay 248, such relay is slow in releasing so that a substitute circuit is provided therefor before such relay iully releases, the substitute circuit being traced from battery through the winding and lefthand contact of relay 248, the normal contact of relay 245 and the middle alternate contact of relay 241 to ground. Relay 248 remaining energized, maintains the circuit in which the windings of relay 247 are in cluded differentially and therefore an impulse of current is not transmitted from office Z in response to the insertion of the plug 13 into the jack 240.

Operator at 077506 W initiates a call over Zine circuit 0.

The operator at ofiice W desiring to cont emporaneously extend another call inserts plug 13 or another link circuit D at oilice W, into jack 60 of line circuit C thereby causing the operation of relays 14 and 61 over a circuit similar tothat previously traced for relays 14 and 21. The closure of the middle alternate contact of relay 61 pro-' duces no material. efiect upon the system since relay 2 is maintained in an operated condition due to the closure of the similar contacts of relays 21 and 41. The closure of the right-hand alternate contact of relay 61 causes the operation otrelay 67 over a circuit extending from battery through the left-hand winding-of relay 67, the right hand alternate contact of relay 61, the righthand normal contact of relay 47, and the right-handnormal contact of relay 27 to ground. Relay 69 is operated over a cir cuit extending from battery through the winding of relay 69, the right-hand alternate contact of relay 67 ,and the right-hand normal contact of relay 27 to ground. In response to the operation of relay 69, relay 68 operates over an obvious circuit and is locked over a circuit extending from battery through the winding and right hand contact of relay 68, the normal contact of relay 65 and the middle alternate contact of relay 61 to ground. The closure of the left-hand contact of relay 68 completes a circuit in cluding the windings of relay 67 connected differentially, and the left-hand contact of relay 68. Relay 67 is thereby released and in releasing causes the release of relay 69, but relay 68 remains in an operated condition due to the locking circuit traced therefor independently of relay 69. Thus relay 67 is thereafter maintained in a. non-operated condition. However, during the operated interval of relay 67, a circuit is completed extending from the positive terminal of the 120 volt source of current through the left-hand alternate contact of relay 67, the right-hand normal contact ofrelays 47 and 27 in series, the upper winding bridged around polar relays 3 and 4, the simplexed conductors of line circuits A and C extending in parallel from office WV to office X, the windings of relays 7 and 6 in series, the windings of relays 81 and 82 in series, the lower winding bridged therearound, the left-hand normal contacts of relays 98, 97, 96 and 94 in series toground. The direction of current flow and the strength of current flowing in this circuit is such as to cause relays 7 and 6 to close their left-hand contacts and'relays 81 and 82 to close their upper contacts. However, no efl'ect is produced by the operation of relays 6 and 7. Therefore, during the continuation of the impluse, relay 87 is operated over an obvious circuit, the closure of the left-hand contact thereof producing no material effect upon the system since relay 80 is locked in an operated condition independently of relay 87. Relay 87 completes a circuit through the closure of its right-hand alternate contact which extends from the posi tive terminal of the 120 volt source of current through the right-hand alternate con tact of relay 87, the right-hand normal con tact of relay 88, the lower winding bridged around relays 92 and 91, the windings of such relays in series, the simplexed conductors of line circuits ii and G extending in parallel from oflice Y to ofiice Z, the wind ings of relays 203 and 20: in series, the lower winding bridged therearound, the right-hand normal contacts of relays 227, 247 and 267 in series, the normal contact of relay 201, and the left-hand normal con tact of relay 202 to ground. The direction of current flow, and the strength of current flowing in this circuit is such that relay 203 closes its upper contact and relay 204 closes its lower contact. However, the closure of the upper contact of relay 203 does not materially affect the system since the upper contact of relay 2% is simultaneously opened. Relay 266 then operates over a circuit extending from battery through the winding of relay 266, the right-hand normal contact of relay 261 and the lower contact of relay 204 to ground. Relays 203 and 20 1 release upon the cessation of the impulse but relay 266 is locked in an operated con dition over a circuit extending from battery through the winding and middle contact of relay 266, and the left-hand normal contact of relay 261 to ground, thereby maintaining lamp 263 lighted over an obvious circuit. The closurev of the left-hand con tact of relay 266 causes the operation of slow release relay 268 over an obvious circuit and the closure of the right-hand con tact of relay 268 completes a circuit in which the windings of relay 267 are in cluded difierentially so that such relay does not operate.

Operator- (ui oficc Z answers the cell being ezrzfcndcd one." Zane carcuzt 0.

The operator at office Z observing the lighted condition of lamp 263 inserts plug 18 of: another link circuit D thereat into the jack 260 whereupon relays 1 1 and 261 operate over a circuit similar to that previously traced for relays 1d and 221. -Belay 266 is released by the opening of the left-hand normal contact of relay 261 thereby extinguishing lamp 263 and although the opening of the left-hand alternate contact of relay 266 opens the operating circuit of relay 268, such relay is slow to release so that a substitute locking circuit is provided therefor. prior to its full release which may be traced from battery through the winding and left-hand contact of relay 268, the normal contact of relay 265, and the middle alternate contact of relay 261 to 'upon the insertion of the ground. Thus relay 267 is maintained "in a non-operated condition independent oflthe operation of rela 261 so that an impulse is not transmitted from office Z to office WV plug into the jack 260.

Qpemtor at 077506 Z transmits the discomect szgnal one?" the line circuit A.

Upon completion of a conversation over line circuit A, the operator at office Z actuates ringing key 18 in the link circuit D associated with the line circuit A at ofiice Z causing the operation of alternating current relay 225 over a circuit extending from the source of alternating current through the lower alternate contact of ringing key 18, the ring contacts of plug 13 and jack 220, the lower normal contact of relay 224, winding of the repeating coil associated with line circuit A, condenser 231 in.series with the winding of relay 225 shunted around the condenser 232, .the upper normal contact of relay 224, the tip contacts of jack220 and plug 13, and the upper alternate contact of key 18 to ground. Relay 230 thereupon operates to short circuit the winding of the repeating coil to efi'ectively prevent inducing the ringing current into the outgoing section of the line. Relay 230 energizes over a circuit extending from battery through the winding of relay 230, the alternate contact of relay 225, and the middle alternate contact of relay 221 to ground. The opening of the normal contact of relay 225 causes the release of relay 228 before relay 280 can close its contacts and upon the opening of the right hand contact of relay 228,.relay 227 is operated over a circuitextending from battery through the righthand winding of relay 227, the left-hand alternate contact of relay 221, and the middle normal contacts of relays 2et7 and 267 to ground. Relay 229 then operates over an obvious circuit to cause the operation of relay 228 overan obvious circuit. Relay 228 in operating looks over a circuit extending from battery throughthe winding and left-hand contact of relay 228, the right-hand contact of relay 230 or the left-hand contact of relay 225, dependingupon whether or not the key 18 has been released and the middle alternate contact of relay 221 to ground. The closure of the right-hand contact of relay 228 includes the windings of relay 227 differentially in a closed circuit thereby releasingsuch relay. The release of relay 227 releases relay 229 but relay 228 remains operated due to the locking circuit traced therefor independently of relay 227. However, during the operated interval of relay227, a circuit is completed extending from the positive. terminal of the 60 volt source of, current through the right-hand alternate contactof relay 227, the upper winding'bridged around relays 203 and 204, the sim olexedconductors of line circuits A and 6 extending in parallel from office Z to ofiiceY, the windings of relays 91 and 92 in series, the lower winding bridged therearound, and the right hand normal contacts of relays 88, 87, 86 and 84 connected in series to ground. The direction of current flow in this circuit is such that relay 91 closes its upper contact, but the strength of current is insuiiicient to cause the operation of marginal relay 92. Therefore during the transmission of the impulse relay 94 is operated over an obvious circuit, the closure of the right-hand alternate contact thereof producing no eiiect upon the system since relay is locked independently thereof, but the closure of the left-hand alternate contact establishes a circuit from the positive terminal of the 120 volt source of current through the resistance 93, the left-hand alternate contact of relay 94, the left-hand normal. contacts of relays 96, 97 and 98 in series, the upper winding bridged around relays 81 and 82, the simplexed conductors of line circuits A and C extending i relays 27, 47 and 67 in series, and the righthand alternate contact of relay 2 to ground.

"- The current flowing through the relays 6 and 7. does not produce any material effect although it causes the relay 7 to close its right-hand contact. The direction of current flowing through relays 3 and 4 is such as to cause relay 3 to close its upper contact,

I but the strength of current is insuflicient to cause the operation of relay 4, therefore during the transmission of the impulse from oflice Y to office WV, a circuit is completed extending from battery through the winding of relay 24, the left-hand alternate contact of relay 21, the upper contacts of relays 3 and 4 in series to ground. Relay 24 responding thereto completes a circuit extending from the source of alternating current through the lower alternate contact of relay 24, ring contacts of jack 20 and plug 13, the lower normal contact of key 18, the lefthand winding of relay 16, condenser 19, the upper normal contact of key 18, the tip contacts of plug 13 and jack 20, and the upper alternate contact of relay 24 to ground. Supervisory relay 16 is energized over such circuit to cause the illumination of supervisory lamp 17 over a circuit extending from battery, the contact of relay 14, the normal contact of key 15, the lower contact of key 16, and the lamp 17 to ground. Relay 16 is locked inan operated condition to maintain the lamp 17 lighted after the cessation of the ringing current over a circuit extending from battery through the contact of relay 14. the normal contact of key 15, the upper Operatorat ofice Z transmits a disconnect signal over the line circmt B.

Upon the completion of the conversation over the line circuit 13, the operator at ofiice Z actuates ringing key 18 causing the operation of relay 245 due to the completion of a circuit extending from the source of alternate current through the lower alternate contact of key 18, the ring contacts of plug 13, and jack 240, the lower normal contact of relay 244, the winding of the repeating coil, condenser'251 and winding of relay 245 shunting the condenser 252, the upper normal contact of relay 244, the tip contacts of jack 240 and plug 13, and the upper alternate contact of key 18 to'ground. The closure of the alternate contact of relay 245 causes the operation of relay 250 for short circuiting the windingof the repeat ing coil to prevent the induction of ringing current into the outward section of the phantom line circuit. The opening ofthe normal contact of relay245 releases relay 248 which in opening its right-hand alternate contact opens the circuit including differentially connected windings of relay 247. Upon the cessation of the applicationof the ringing current relay 245 releases and causes the release of relay 250. Relay 247 operates over a circuit extending from battery through the right-hand winding of relay 247, the lefthand alternate contact of relay 241, the left-hand normal contact of relay 267 and the left-hand normal contact of relay 227 to ground. Relay 249 operates over a circuit extending from battery through the winding of relay 249, the left-hand alternate contact of relay 247, and the righthand normal contact of relay 227 to ground. The operation of relay 249 causes the operation of relay 248 over an. obvious circuit, the latter relay looking over a circuit completed, upon the release of relay 245, from battery through the winding and left-hand contact of relay 248, the normal contact of relay 245 and the middle alternate contact of relay 241 to ground. The closure of the right-hand contact of relay 248 completes a circuit in which the windings of relay 247 are again differentially included causing the release of the latter relay which in pe g s l ft-h n a t rnate Contact causes the release of relay 249. However, relay 248 does not r lease due to th loci-:- ing circuit previously completed. During the interval in which relay 247 is. in an operated condition a circuit is completed "from the negative terminal of the 60 volt source of current through he right-hand alternate contact of relay 247, the right-hand normal contact of relay 227, the upper winding bridged around polar relays 203 and 20 1, the simplexed conductors of line circuits A and U extending in parallel from oilice Z to oflice Y, the windings of relays 91 and in series, the lower winding bridged therearound, and the righthand normal contacts of relays 88, 87, 86 and 84 in series to ground. The direction of current flow in this circuit is such that relay 91 closes its lower contact but the strength of current is insuthcient to cause the operation of marginal relay 92. Therefore during the con tinuation of the impulse, relay 96 is operated over an obvious circuit. The closure of the right-hand contact of relay 96 produces no material effect upon the system since relay '80 is locked independently of such relay, but theclosure of the left-hand contact of relay 96 completes a temporary circuit extending from the negatiye terminal or". the 120 volt source of current through resistance 95, the lett-hand alternate contact of relay 96, the left-hand normal. con tacts of relays 97 and 98 in series, the upper winding bridged around relays S1 and 82. the simplexed conductors of line cir cuits A and C extending in parallel from office Y to oflice X. the windings of relays 6 and 7 in series, the simplexed conductors ot line circuits A and C extending in parallel from otlice X to ofiice W, the windings oft relays 3 and at in series, the lower wind ing bridged therearound, the left-hand normal contacts of relays 27, 47 and 67 in series, and the right-hand alternate contact of relay 2 to ground. The direction of current flowing through this circuit is such as to cause relay 7 to close its left-hand contact, and relay 3 to close its lower contact. However, insufficient current is flowing there through due to the inclusion of resistance 95 therein to cause the operation of relays 4E and 6. l lo-effectis produced upon the circuit upon the closure of the contact or" re-- lay 7, inasmuch as relay 8 is locked inde pendently or" relay 7. The closure of the lower contact of relay 3 in response to the impulse transmitted causes the operation of relay el during the transmission of such an impulse over a circuit extending from battery through the winding of relay 4a, the left-hand alternate contact of relay e1, the lower contact of relay 3, and the upper contact of relay 4 to ground. The operation of relay 44L- completes a circuit extending from the source of alternating current through the current flowing in this circuit, relay J6 is operated to cause the illumination o supervisory lamp 17 over a circuit similar to that traced in the previous instance and relay 16 thereupon locks over the circuit described in connection with line circuit In response to the display of the visory si 'nal 17, the operator at otlice il removes plug 13 from jack 4:0 causing the release of relays 14, 41 and 48. However, relay 2 does not release since the middle alternate contact of relay 61 remains closed. The subsequent removal 01"- the plug 18 ot the link circuit D at ofiice Z from aclr 2 H similarly causes the release of relays 14, 241 and 248.

Operator at 077506 Z transmits a. disconnect szgnal over the Zme oircwt 0.

Upon the completion of the conversation over line circuit C, the operator at otlice Z actuates ringing key 18 in the link circuit D thereat associated with line circuit C coinpleting a circuit extending from the source of alternating current through the lower alternate contact of key 18, the ring con tacts of plug 13 and jack 260, the lower normal contact of relay 264, the windin of the repeating coil, condenser 271, and relay 265 in series shunted around condenser 272, the upper normal contact of relay 26st, the tip contacts of jack 260 and plug 13, and the upper alternate contact of key 18 to ground. The closure of the alternate contact of relay 265 causes the operation of relay 27 O which, as in the previous cases. short circuits the winding of the repeating coil to prevent the transmission of the ringing current over the line circuit C. The opening of the normal contact or the relay 265 causes the release of relay 268. Upon the cessation of the application of ringing current, relay 265 releases and causes the release of relay 270.

The opening of the right-hand alternate contact of relay 268 opens the relcasi cult of relay 267 which included the wind ings of such relay differentially connected. Relay 267 then energizes over a circuit through its right winding, left alternate contact of relay 261, left normal contact oi relay 24-7, to ground at the left normal contact of relay 227. Belay 269 then energizes which causes the re-operation o't relay 268 over an obvious circuit. Relay 26S locks over a circuit extending from battery through the winding and left-hand contact cirthereof, the normal contact of relay 265 and the middle alternate contactof relay 261 to ground. The closure of the right-hand contact of relay 268 re-establishes the releasing,

circuit for relay 267 in which the windings of such relay are included differentially. The opening of the lett-hand alternate contact of relay 267 causes the release 01 relay 269, but relay 268 remains locked over the circuit traced therefor. During the period in which relay 267 remains operated, a circuit is completed extending from the positive terminal of the 120 volt source or" current through the right-hand alternate contact of relay 267, the right-hand normal contacts of relays 247 and 227 in series, the upper winding bridged around relays 203 and 204, the simplexed conductors of line circuits A and C extending in parallel from oflice Z to oflice Y, the windings of relays 91 and 92 in series, the lower winding bridged therearound, and the righthand normal contacts of relays 88, 6", 86 and S4 in series to ground. The direction of current flow in this circuit, and the strength of current flowing therein is such as to cause relays 91 and 92 to close their upper contacts. Therefore, during the continuation of the impulse, relays 94 and 97 are operated over an obvious circuit, the operation of relay 94 however, producing no material effect upon the system since the back contact of relay 97 is opened before the lefthand alternate contact of relay 94 is closed. The closure of the right-hand alternate contact or relay 97 produces no material elfect upon the system since relay 80 is locked independently of relay 97 but the closure of the left-hand alternate contact of relay 97 completes a temporary circuit extending from the negative terminal of the 120 volt source of current through the left-hand alternate contact of relay 97,

the left-hand normal contact of relay 98,

the upper winding bridged around polar relays 81 and 82, the simplexed conductors of line circuits A and C extending in parallel from office Y to otlice X, the windings of relays 6 and 7 in series, the simplexed conductors of line circuits A and C extending in parallel from office X to office "W, the windings of relays 3 and 4 in series, the lower winding bridged therearound, the left-hand normal contacts of relays 27, 47 and 67 in series and the right-hand alternate contact of relay 2 to ground. The direction of current flow, and the strength of current flowing in this circuit is such as to cause relays 6 and 7 to close their left-hand contacts, relay 3 to close its upper contact and relay 4 to close its lower contact. The operation of relay 3 produces no material effect upon the system since the upper normal contact or relay 4 is also opened. Therefore, during the continuation of the impulse, relay 64 operates over a circuit extending from battery through the winding 01 relay 64, the lefthand alternate contact of relay 61 and the lower contact of relay 4 to ground. The operation of relay 64 completes a circuit extending from the source of alternating current through the lower alternate contact of relay 64, the ring contacts of jack 60 and plug 13, the lower normal contact of key 18, the left-hand winding of relay 16, the condenser 19, the upper normal contact of key 18, the tip con tacts oi plug '18 and jack 60, and the upper alternate contact of relay 64 to ground. As in the previous instances relay 16 responds to such current to cause the illumination of lamp 17 and locks over a circuit similar to that previously described.

In response to the lighted condition of supervisory lamp 17, the operator-at oflice W removes plug 13 from jack 60 thereby releasing relays 14 and 61. The opening of the middle alternate contact of relay 61 not only causes the release of relay 68, as

in the previous similar instances, but also due to the opened condition of the similar contacts of relays 21 and 41 causes the release of relay 2. The opening of the middle alternate contact of relay 2 causes the release of relay 1, but due to the slow release nature of this relay, a temporary circuit is established from the negative terminal of the 120 volt source of current through the alternate contact of relay 1, the left-hand normal contacts of relays 67 47 and 27 in series, the upper winding bridged around polar relays 3 and 4, the simplexed conduc- ,tors of line circuits A and C extending-in parallel from ofilce W to oilice X, the windings of relays 7 and 6 in series, the simpleXed conductors of line circuits A and C extending in parallel from office X to oflice Y, the windings of relays 81 and 82 in series, the lower winding bridged therearound, and the lefthand normal contacts of relays 98, 97, 96 and 94 in series to ground. The direction of current flow in this circuit, and the amount of current flowing therein is such as to cause relays 7 and 6 to close their right-hand contacts and relays 81 and 82 to close their lower contacts. The operation of relay 7 produces no material effect upon the system, but the operation of relay 6 causes the operation of relay 5 over an obvious circuit, and the opening of the normal contact of the latter relay causes the release of relay 8 which in opening its right-hand and middle contacts disables the filament battery supply circuits for repeaters HA and RC associated with line circuits A and C respectively. Relay 5 restores upon the cessation of the impulse and relay 6 reassumes its normal condition. Relays 86 and 88 are operated by the closure of the lower contacts of relays 81 and 82 but the operation of relay 86 has no effect ofiice .4 and office Y.

since the right hand contact of relay '99 is opened before the left hand alternate contact of relay S6 is closed. The opening of the left-hand co tact of relay 88 opens the locking circuit i-or relay 80 allowing such relay to release-and through the opening of its right-hand and middle contacts to disable the filament battery supply circuits repeaters HA and RC associated with the line circuits A and C respectively at The opening of the right-hand contact of relay 88 also prevents the transmission of a signal to office Z. Upon the operator Z removing the plug 13 from the jack 260, relays 14 and261 release causing the release of relays 268, 202 and in a manner similar to that described for the corresponding relays at office l i hat claimed is:

1. In a telephone system, distant oflices, onerators positions thereat, a plurality of 'ssicn lines connecting said offices, a

uit connected to certain of said ms at each office operable to transmit a signaling impulse over said signaling circuit and the lines connected. thereto to another office, means at said other-office responsive to said impulse for indicating the line over Which a call hasbeen initiated, and means said otheroi'iice for preventing the operation of the first-named means thereat when the operator at said other office res onds to the initiated call.

2. in a telephone system, distant offices, perators positions thereat, a plurality of transmission lines interconnecting said ofdoes, a signaling circuit connected to certain said lines, a relay at each ofice operable transmit a signaling impulse over said signaling circuit and the lines connected thereto to the other office, means. at the other office responsive to said impulse for indicating the line over which a call has been initiated, and means at said other office for preventing the operation of said relay thereat when the operator at said other oflice responds to an initiated call.

3. In a telephone system, distant ofiices, operators positions thereat, physical and phantom lines interconnecting said ofiiccs, a signaling circuit connected to said physical lines, means at each ofiice operable to transmit a signaling impulse over said signaling circuit and said physical lines to the other office, means at said other office responsive to said impulse for indicating the line over which a call has been initiated, and means at said other office for preventing the operation of the. first-named means thereat when the operator at said other office responds to an initiated call.

i. In a telephone system, distant offices, operators positions thereat, physical and phantom circuits interconnecting said ofiices,

a signaling circuit connected to said physical lines, a relay at each office operable'to transmit a signaling impulse over said signaling circuit and said physical lines in parallel to the other office, means at said other office responsive to said impulse for indicating the line over which a call has been initiated,-and means at said other oflice for preventing the operation or" the relay thereat when the operator at said other office responds to the initiated call.

5. In a telephone system, call initating and terminating offices, a plurality of transmission lines interconnecting said offices, a signaling circuit connected to certain of said lines and including them in parallel, a link circuit, .means atsaid initiating office responsive to the connection of said link circuit to one of said lines for transmitting a signaling impulse over said signaling circuit, and means at "said terminating office responsive to the lastnamedmeans for selectively determining 'thereat the particular line over Which a call is initiated.

6. In a telephone system, call initiating and terminating oflices, physical and phantom lines interconnecting said oflices,.a signaling circuit connected to said physical lines and including them in parallel, a link circuit, means at said initiating office sponsive to the connection of said link circuit to one of said lines for transmitting a signaling impulse over said signaling circuit, and means at said terminating office responsive t0 the last-named means for indicating thereat the particular line over which a call is initiated.

7. In a telephone system, two distant offices, intermediate ofiices, physical and phantom lines interconnecting said offices, a signaling circuit connected to said physical lines and including them in parallel, means at one of-said distant offices for transmitting a signaling impulse over said signaling circuit, polar relays at one of said intermediate offices responsive to said signaling impulse for transmitting alike impulse to the other distant office, and means at the latter ofiice responsive to the signaling impulse for indicating at said other office the particular line over Which a call has been initiatec 8. In a telephone system, distant and intermediate offices, physical and phantom circuits interconnecting said ofiices, a signaling circuit connected to said physical lines and including them in parallel, means at one of said distant ofiices for transmitting a signaling impulse over said signaling circuit, repeaters at said intermediate ofiice associated with said physical lines, means at each intermediate office responsive to the signaling impulse transmitted for rendering effective the repeaters at the respective intermediate offices, and means at the other distant ofiice responsive to said signaling impulse for indieating the particular line over which a call has been initiated.

- 9. In a telephone system, distant and intermediate ofiices, physical and phantom lines interconnecting said offices, a signaling circuit connectedto said physical lines and including them in parallel, means at one of said distant oilices for transmitting signaling impulses over said signaling circuit, repeaters for the physical circuits at one of said intermediate ofiices, polarized relays responsive to a signaling impulse for rendering said repeaters effective, other repeaters associated with the physical lines at the other intermediate oflice, means including the polarized relays responsive to said signaling impulse for rendering said other repeaters effective and for transmitting a like impulse to the other distant office, and means at the latter office responsive to said signaling impulse for indicating thereat the particular line over which a call has been initiated.

10. In a signaling system, terminating and intermediate ofiices, a plurality of transmission lines, a signaling circuit common to said lines, means at each terminating oflice for transmitting a signaling impulse over saidsignaling circuit and certain of said lines, a plurality of switching devices at an intermediate office, one of which is selectively responsive to said impulse to repeat the same at said intermediate ofiice for transmission to a terminating office, and means at the latter ofiice responsive to the repeated impulse for indicating the line over which the call has been initiated.

11. In a signaling system, terminating and intermediate offices, a plurality of transmission lines, a signaling circuit common to said lines, means at a terminating office for transmitting signaling impulses over said'signaling circuit and certain of said'lines, a plurality of switching devices at an intermediate oflice responsive to said impulses and cooperating to repeat the same at said intermediate office for transmission to the other terminating office, and means at the latter office responsive to the repeated impulses for indicating the line over which a call has been initiated.

12. In a signaling system, a plurality'of V two-way transmission lines, a repeater-associated with each line, and means responsive to the seizure of any one of said lines V for rendering operative all of said repeaters. 13. In a signaling system,,.-a plurality of two-way transmission lines, repeaters asso- V ciated with said lines, means for energizing said repeaters when connections are estab lished over said lines, and meansresponsive when all connected lines are disconnected todeenergize all of said repeaters.

14. In a signaling system, more than two transmission lines extending between two OlllCQS, a signaling path common to said lines, a pluralityof relaysand more than two sources of current at oneend of said common signaling path, means responsive to the seizure of any one of said lines for operating a combination of said relays to select one of said plurality'ot sources of current identifying the line seized and to connect the selected source of current to the common signaling path, and means at" the other end of said common signaling path responsive to the selected source of current for identifying the line seized.

15. In a signaling path, a plurality'of' at the other end of said common signaling pat-h responsive to the selected source of current for identifying the line seized.

In witness whereof, I hereunto subscribe my name this 26th day o't December, A. D. 1919.

WILLIAM H. HARRISON. 

